This is the new forwarding code for 636.  It
uses multicast emulation to create two othernets,
and allows the user to configure the machine as a
host on Othernet1, a host on Othernet2, or a
router that connects both Othernets to the lab
Ethernet (which leads to the Internet).  When
configured as a router, the code performs NAT
for UDP and ICMP (ping only) messages.  Thus, a
host on an Othernet can send UDP or ping an
arbitrary Internet site.  For example, the date
command sends UDP to a time server on 128.10.3.8.

The code started with the X86 reference version.
